The invention relates to a method and apparatus for the preparation of calcium hydroxide, in particular for a mobile system that facilitates the continuous preparation of calcium hydroxide slurry from calcium oxide and water at a jobsite location.
The use of calcium hydroxide slurries to stabilize clay soils in highway and general construction projects is well established.
When preparing calcium hydroxide slurry by mixing calcium oxide and water together, a highly exothermic reaction takes place. Generally apparatus designed for this process have been of a batch nature, or a limited capacity continuous process.
What is therefore needed is a slaking and mixing apparatus that is mobile.
What is also needed is a slaking and mixing apparatus capable of processing high hourly volumes and servicing a fleet of mobile slurry spreading tankers through high volume intermittent output from the apparatus.
It is therefore an object of the invention to provide an apparatus to continuously process high volumes of calcium oxide up to a rate approximating 30 tons per hour.
Another object of the invention is to provide a continuous slurrying/slaking process which has provision to discharge either into a static slurry storage tank, or to discharge intermittently into a fleet of mobile tankers for spreading the product at the jobsite
Another object of the invention is to provide an apparatus that allows for accurate and infinitely variable consistency of the product slurry as measured in percentage solids.
Another object of the invention is to provide an apparatus that can be mounted on a trailer, easily moved to a job site and set up in a minimal time.
Another object of the invention is to provide a lime slaker that requires only a source of water, a commercial lime delivery, and slurry distribution trucks or a storage tank for production. In this way, the slaker can be used economically on smaller jobs where current methods cannot be justified because of the high set-up costs.
Another object of the invention is to provide an apparatus that permits accurate blending of calcium oxide and water in a continuous process that can produce limited quantities of lime slurry necessary for small job site, or larger quantities of lime slurry for larger job sites.
Another object of the invention is to provide an apparatus capable of producing high shear and turbulent mixing of calcium oxide and water through the use of an eductor designed to promote initial mixing, agitation in the system tanks created by high velocity streams from the system pumps directed through specifically designed flow devices to achieve maxium turbulence, high shear mixing within the slurry pump and differential velocity mixing in the serpentine centrifugal mixer.
According to one aspect of the invention, the equipment is fully mobile, self-contained and designed to be pulled by a small pick-up truck requiring only delivery of the two chemical components, calcium oxide and water, at the jobsite.
According to one aspect of the invention, the apparatus includes variable and accurate dosing of the chemical components, thus ensuring the required slurry consistency.
According to one aspect of the invention, the apparatus includes an eductor to provide intimate mixing of the two chemical components.
According to one aspect of the invention, a serpentine centrifugal mixer is used to achieve a high shear rate between the components of the slurry, thus ensuring full conversion of the calcium oxide to calcium hydroxide.
According to another aspect of the invention, the calcium oxide and water mixture is subjected to pressure during the later stages of hydration, forcing water into any remaining unhydrated particles, assuring complete. hydration.